"We're still sort of coming to grips with what has happened, but it looks like they have been swimming in quite shallow water, about seven metres of water, they had two dolphins right by [her] side and we believe that the shark has come in from the bottom," he said.

Department of Fisheries spokesman Tony Cappelluti says it is yet to be determined exactly what type of shark it is.

"The latest report is possibly a three-metre whaler shark," he said.

"Earlier reports indicated it could have been a white pointer but they could not be sure. But the latest description with a blunt nose suggests it wasn't a white pointer, possibly a whaler species."

Mr Cappelluti says the woman was the woman was first taken to HMAS Stirling, located at a nearby naval base for treatment.

"It's my understanding the medics there provided her with some treatment and then she was was flown to Royal Perth Hospital," he said.

He says authorities spent much of the afternoon trying to locate the shark.

"The Surf Life Saving helicopter was dispatched area to search for the shark my understanding there were no further sightings," he said.

"Because the shark wasn't resighted our boat was required and I am not sure about our operation for tomorrow but I would suggest the helicopter will be up again.

"It will probably keep a watching brief on the area and we will be ready to respond with the water police if need be."

The site of the attack is just kilometres from where 51-year-old Brian Guest was taken by a large great white as he dived in December 2008.

And in August this year, Busselton man Nick Edwards, 31, was killed by a shark when he was surfing at Gracetown beach, south of Perth.